pc7:~ mptorz$ sudo pip uninstall web.py
Password:
The directory '/Users/mptorz/Library/Caches/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Uninstalling web.py-0.40.dev0:
/usr/local/lib/python2.7/site-packages/web.py-0.40.dev0-py2.7.egg
Proceed (y/n)? y
Successfully uninstalled web.py-0.40.dev0
The directory '/Users/mptorz/Library/Caches/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.

Then I tried to do this:

pc7:~ mptorz$ sudo pip install web.py
The directory '/Users/mptorz/Library/Caches/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/Users/mptorz/Library/Caches/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Collecting web.py
Downloading web.py-0.38.tar.gz (91kB)
100% |████████████████████████████████| 92kB 199kB/s
Installing collected packages: web.py
Running setup.py install for web.py ... done
Successfully installed web.py-0.38

When I run the app I still get the same error 'ImportError: No module named web'.

I was asked to add the result of python -c "print(import('sys').path)":